This invention relates to an in-line wire drawing machine of the type which pulls a length of wire through a drawing die and supplies the wire to a using station where a production machine such as a cold header performs an operation on the wire. More particularly, the invention relates to a wire drawing machine of the same general type as disclosed in Lathom et al U.S. Pat. No. 3,280,611; Guthrie U.S. Pat. No. 3,402,588 and Alcock U.S. Pat. No. 3,646,798.
In such a wire drawing machine, a coil of wire is wrapped around a rotatable drum. When the drum is rotated, wire is drawn through the die and wound onto one end of the drum and, at the same time, wire is unwrapped from the other end of the drum and is delivered to the production machine. The speed of rotation of the drum must be matched to the demand of the production machine and, for this purpose, the drum is rotated by a variable speed drive mechanism which may be adjusted manually to cause the drum to rotate at a selected speed. In those instances where the variable speed drive mechanism is of the mechanical type, provision is made to momentarily shut off the drive motor when the drum is supplying more wire than can be consumed by the production machine. If the drive mechanism is of the hydrostatic type or if the drive mechanism incorporates a slip clutch, provision is made to automatically trim the speed of the drum in order to equalize the supply of wire with the requirements of the production machine. To stop the drum or adjust its speed, a pivoted compensator arm is biased into engagement with a loop of wire after the wire leaves the drum. When the speed of the drum is too great, the size of the loop increases and the arm swings in one direction to either shut off or slow down the drive to the drum. If there is an insufficient supply of wire, the loop decreases in size and causes the arm to swing in the opposite direction so as to either restart the drive or increase its speed.
It is desirable to obtain maximum traction between the wire and the drum in order to develop sufficient force to pull the wire through the drawing die and to prevent the wire from slipping on and galling the drum. Also, it is desirable that the wire leave the drum with minimum tension so that the wire will not pull back on the production machine. Prior arrangements for achieving these aims, however, are both complicated and expensive.